1 / 21

COS 420

COS 420. DAY 25. Agenda. Assignment 5 posted Chap 22-26 Due May 4 Final exam will be take home and handed out May 4 and Due May 10 Today we will discuss Electronic Mail (SMTP, POP, IMAP, MIME). Project 2 Grading. Meeting Timelines 10% Deliverables

clemance-legend
Télécharger la présentation

COS 420

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. COS 420 DAY 25

  2. Agenda • Assignment 5 posted • Chap 22-26 • Due May 4 • Final exam will be take home and handed out May 4 and Due May 10 • Today we will discuss Electronic Mail (SMTP, POP, IMAP, MIME)

  3. Project 2 Grading • Meeting Timelines 10% • Deliverables • Program requirements Due March 30 15% • late • Protocol Definition Due April 13 15% • Better but I hope to see improvement by May1 • Working Network Application Due May 4 25% • Final Paper Due May 1 25% • User Manual • Protocol • Program requirements • Technical Specifications • Presentation Due May 4 10%

  4. Electronic Mail • Among most widely used Internet services • Two major components • User interface • Mail transfer software • Paradigm: transfer is separate background activity

  5. Illustration Of Email System Components

  6. Mailbox Names And Aliases • Email destination identified by pair ( mailbox, computer ) • Aliases permitted (user enters alias that is expanded)

  7. Forwarding • Powerful idea • Email arriving on a computer can be forwarded to an ultimate destination

  8. Illustration Of Aliases And Forwarding

  9. TCP/IP Standards For Email • Syntax for email addresses • Format of email message • Protocols for email transfer and mailbox access

  10. Email Address Syntax • Mailbox identified by string mailbox@computer • String computer is domain name of computer on which a mailbox resides • String mailbox is unique mailbox name on the destination computer

  11. Format Of Email Message • Message consists of • Header • Blank line • Body of message • Headers have form keyword : information • Standard given in RFC 2822

  12. E-mail header Return-Path: <voisine@maine.edu> Received: from granite.unet.maine.edu ([unix socket]) by granite.unet.maine.edu (Cyrus v2.2.12-Maine-RPM-2.2.12-3.RHEL4.1.um.2) with LMTPA; Fri, 28 Apr 2006 14:16:12 -0400 X-Sieve: CMU Sieve 2.2 Received: from VoisineScott (VoisineScott.umfk.maine.edu [130.111.68.129]) by granite.unet.maine.edu (8.13.1/8.13.1) with ESMTP id k3SIEdHh000307; Fri, 28 Apr 2006 14:15:06 -0400 From: "Scott Voisine" <voisine@maine.edu> To: "Scott Voisine" <voisine@maine.edu> Subject: EDU 405 Play Date: Fri, 28 Apr 2006 14:14:39 -0400 Message-ID: <003101c66aef$a9e2f830$81446f82@NETUMFK.EDU> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0032_01C66ACE.22D15830" X-Mailer: Microsoft Office Outlook 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 Thread-index: AcZq75BMY/2KYcRVRGurpMOPNTltNA== X-MailScanner-Information: Please contact the ISP for more information X-MailScanner: Found to be clean X-MailScanner-From: voisine@maine.edu

  13. Protocol For Email Transfer • Specifies interaction between transfer components • Transfer client • Transfer server • Standard protocol is Simple Mail Transfer Protocol (SMTP)

  14. SMTP • Application-level protocol • Uses TCP • Commands and responses encoded in ASCII

  15. Example Of SMTP

  16. Protocol For Mailbox Access • Used when user’s mailbox resides on remote computer • Especially helpful when user’s local computer is not always on-line • Two protocols exist • Post Office Protocol version 3 (POP3) • Internet Message Access Protocol (IMAP) • Each provides same basic functionality • User authentication • Mailbox access commands

  17. Multipurpose Internet Mail Extensions (MIME) • Permits nontextual data to be sent in email • Graphics image • Voice or video clip • Sender • Encodes binary item into printable characters • Places in email message for transfer • Receiver • Receives email message containing encoded item • Decodes message to extract original binary value

  18. MIME Header • Header in email message describes encoding used • Example From: bill@acollege.edu To: john@example.com MIME-Version: 1.0 Content-Type: image/jpeg Content-Transfer-Encoding: base64 ...data for the image...

  19. Seven Basic MIME Types

  20. Example Of Mixed / Multipart Message

  21. Summary • Email operates at application layer • Conceptual separation between • User interface • Mail transfer components • Simple Mail Transfer Protocol (SMTP) • Standard for transfer • Uses ASCII encoding • Post Office Protocol (POP) And Internet Mail Access Protocol (IMAP) allow access of remote mailbox. • Multipurpose Internet Mail Extensions (MIME) permits transfer of nontextual information (e.g., images)

More Related